如何在相对布局中居中两个视图？

Question

The task is simple: there are two buttons and a TextView above them. All the widgets shoud be centered within the relative layout. The only one idea I have is create the third widget View and use it as a center axis for the buttons. Any ideas? A redundant layout isn't a good solution.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <TextView
        android:id="@+id/tv_progress"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        android:text="@string/app_name" />

    <View
        android:id="@+id/view_axis"
        android:layout_width="1dp"
        android:layout_height="1dp"
        android:layout_below="@id/tv_progress"
        android:layout_centerInParent="true" />

    <Button
        android:id="@+id/button_start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv_progress"
        android:layout_toLeftOf="@id/view_axis"
        android:text="@string/start" />

    <Button
        android:id="@+id/button_stop"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/tv_progress"
        android:layout_toRightOf="@id/view_axis"
        android:text="@string/stop" />

</RelativeLayout>

Answer 1

If I understand what you want correctly, you can put the Button s in a LinearLayout and center that

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<TextView
    android:id="@+id/tv_progress"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:text="@string/app_name" />
<LinearLayout
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_below="@id/tv_progress">
<Button
    android:id="@+id/button_start"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/start" />

<Button
    android:id="@+id/button_stop"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/stop" />
 </LinearLayout>

I'm not sure if that's what you meant by a "redundant layout" but doing this is fine if it gives you what you want.

Answer 2

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="match_parent"
   android:layout_height="match_parent">

    <Spinner
        android:id="@+id/sp_rooms"
        android:layout_toLeftOf="@id/space"
        android:layout_centerVertical="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Space
        android:id="@+id/space"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/btn_registration"
        android:layout_centerVertical="true"
        android:layout_toRightOf="@id/space"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</RelativeLayout>

Answer 3

This will vertically and horizontally center the whole block consisting of the textview + buttons

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_centerInParent="true">

        <TextView
            android:id="@+id/tv_progress"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/app_name" />

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal" >

            <Button
                android:id="@+id/button_start"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/start" />

            <Button
                android:id="@+id/button_stop"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="@string/stop" />      

        </LinearLayout>

    </LinearLayout>

</RelativeLayout>